FIELD OF THE INVENTION
The present invention relates to seat recliners for a vehicle, and more specifically to seat recliners using a so-called taumel gearing that employs intermeshing spur and ring gear elements.
One example of such recliners includes two relatively moveable brackets connected with a seat cushion and a seat back, respectively. The brackets are connected with each other in an eccentric relation through a shaft. The shaft is supported at its one end by a base or cover member that is fixed to one of the brackets. The brackets have intermeshable internal and external teeth, respectively. A pair of wedges are disposed on the shaft in a circumferentially spaced relation to each other. A spring biases the wedges so as to be apart from each other and moved toward a radial projection that is disposed on the shaft. The wedges and the spring cooperate to eliminate a radial play or clearance between the internal and external teeth of the brackets at the intermeshing position to thus surely retain one of the brackets at a desired position relative to the other bracket.
In such conventional recliners, it is likely that the wedges are undesirably displaced from the axial position on the shaft upon rotation of the shaft. This is because an axial space for accommodating the spring is produced between the wedges and the base member becomes too large so that there is no support for the wedges in an axial direction of the shaft.
In order to restrict the undesired displacement of the wedges, there has been proposed an arrangement in which the spring includes a portion extending along an axial end face of each wedge. This arrangement, however, will perform insufficient retention of the wedges in the axial position because of the spring being made of a wire material. Further, since a non-uniform axial space between the wedges and the base member tends to be produced, it will occur that the spring remains pressed against the wedges and locked up thereon in a case where the axial space is partly smaller than a diameter of the spring. This will cause influence on the movement of the wedges upon rotation of the shaft, leading to insufficient performance of the wedges in elimination of the play between the intermeshing teeth of the brackets.
Otherwise, it will be proposed that a retainer for the wedges is provided as a separate part. In such a case, the total number of parts of the seat recliner will be increased and then the manufacturing cost will be raised.
An object of the present invention is to provide an improved seat recliner for a vehicle which has a simple structure and is capable of holding the wedges in a proper position where the wedges can surely operate during rotation of the shaft in operation of the seat recliner.